I don't think the issue is interference. I think the issue is that most accidents happen during takeoff and landing, so having iPads flying around in case of severe turbulence or having iPads line the aisle during an evacuation would be bad.

First of all, the regulations call for mobile communication devices such as iPads to never be used during flight. There have been times I've been told to turn off my iPad during cruise even if it was in "Airplane mode." During takeoff and landing, they ask passengers to stow ALL items under the seat or in the overheads. If you think this article is vouching for use of iPads during takeoff and landing, you are mistaken. Second of all, you also mentioned severe turbulence which can happen at any phase of the flight. My point stands that if you believe their justification for banning use of iPads during the flight is due to the possibility of them flying around during severe turbulence, it's inconsistent logic.

The regulations call for for mobile devices to not be used in flight until 10,000ft, which then can devices with a game-only or airplane mode be used. Anything else with a radio device must remain off.

Either way, that is what the FCC is challenging, as it is those radio devices that RECEIVE ONLY that can not be allowed to be turned in Part 121 operations (commercial flights).

You should also note that this regulation does NOT apply for Part 91 (General Aviation/fractional) nor Part 135 (Charter/commuter/on-demand) operations, so you have ambiguity there on what the actual problem is. So it seems to me that with that ambiguity, either the regulation is not being applied across the board as it should be, or the regulation is wrong because the potential threat of what those devices could do is not real nor has been completely proven.

The chairman of the FCC has sent a letter to the Acting Administrator of the FAA asking that the agency reconsider its ban on the use of some portable electronic devices during takeoff and landing. FCC Chairman Julius Genachowski wrote that the FAA should "enable greater use of tablets, e-readers, and other portable devices" during commercial flights.